The present invention relates generally to an electrical circuit assembly, and more particularly to an electro-mechanical connection between a microchip and a substrate.
Integrated circuit devices (i.e., microchips, chips, or dies) are typically connected to a substrate (e.g., chip carrier, package, or circuit board) using well-know methods such as Direct Chip Attach (DCA) and wire bonding. DCA uses joining materials such as metallurgical solders or polymeric conductive adhesives that are typically applied to the electrical connection pads (i.e, bond pads) of the chip. The chip can then be electromechanically connected to corresponding bond pads on a substrate by applying heat to melt, or reflow the solder. A protective polymer, called underfill, is applied to the gap between the chip and substrate and then hardened by heating to cause the liquid to polymerize to a solid and provide further bonding between the chip and substrate. In wire bonding, an adhesive or solder is used to attach the chip to the substrate. After chip attachment, fine metal wires are then welded to each chip electrical connection pad and to the corresponding substrate electrical connection pad by using heat or ultrasonic energy. Reference may be made to U.S. Pat. Nos. 5,439,162 and 5,665,654, both of which are incorporated by reference herein for all purposes, for additional background information relating to DCA and wire bonding chip attachment processes. While DCA and wire bonding processes typically result in a reliable chip connection, the connection is considered permanent and does not allow removal and reconnection of the chip. Also, the heat required to reflow the solder or adhesive may damage the microchip and decrease production efficiencies.
Existing electro-mechanical chip connection methods that eliminate thermal bonding processes allow a conventional microchip device to be electrically and mechanically mounted on a substrate of the circuit so that the chip can be removed and reconnected without heating the chip or the substrate. These conventional electro-mechanical connection methods typically include metallized interlocking structures (i.e., hook and loop configurations, interlocking inserts, interlocking micromechanical barbs) located on the electrical connection pads of the microchip and the substrate. Reference  may be made to U.S. Pat. Nos. 5,411,400, 5,774,341, and 5,903,059, which are incorporated by reference herein for all purposes, for additional background information relating to existing reconnectable electro-mechanical connections between an integrated circuit device and a substrate. Existing reconnectable chip interface structures have not seen widespread acceptance in the industry because of high manufacturing costs and low reliability of operation.